1. Field of the Invention
The present invention relates to a transistor array panel, a liquid crystal display panel, and a method of manufacturing a liquid crystal display panel.
2. Description of the Related Art
An active matrix driving type liquid crystal display panel has a structure in which a transistor array panel is disposed to face a counter substrate, and a liquid crystal is sandwiched between the transistor array panel and the counter substrate. The liquid crystal display panel is formed by patterning thin-film transistors, pixel electrodes and the like in a matrix form on a substrate such as a transparent glass substrate. The counter substrate is constracted by forming a counter electrode and the like all over itself.
The conventional transistor array panel includes a plurality of gate lines arranged in a row direction, and a plurality of data lines arranged in a column direction. The thin-film transistors and the pixel electrodes are formed in intersecting portions between the gate lines and the data lines. A region where the plurality of thin-film transistors and pixel electrodes are arranged in the matrix form is referred to as a display region.
The gate lines are connected to lead-in wiring lines on a left or right side of the display region, and electrically connected to a driving circuit via the lead-in wiring lines. The data lines are connected to lead-in wiring lines on an upper or lower side of the display region, and connected to the driving circuit via the lead-in wiring lines.
In an outer peripheral portion of the display region where the pixel electrodes are arranged, to protect the gate lines and the data lines from static electricity, protective lines electrically connected to the gate lines and the data lines via a protective element, and annular common lines of a protection circuit connected to the protective lines via resistance elements are disposed to cross the gate lines and the data lines at right angles.
The common line and the protective line of the protection circuit, and the gate lines crossing the data lines at right angles are formed by patterning an all over formed conductive film (gate metal film) simultaneously with the gate electrodes of the thin-film transistors and the gate lines. The common line and the protective line of the protection circuit, and the data lines crossing the gate lines at right angles are formed by patterning another all over formed conductive film (drain metal film) on a gate insulating film coated with the gate metal film simultaneously with source and drain electrodes of the thin-film transistors and the data lines. There are insulated, by the gate insulating film, a portion between the gate line and the data line and a portion between the gate and data line and the common and protective line of the protection circuit crossing the gate and data lines at right angles.
The common line of the protection circuit made of the gate metal film or the drain metal film conducts electricity owing to a contact hole extending through the gate insulating film in the intersecting portion, and the common line is annularly formed. Each of the protective element and the resistance element is made of the gate metal film or the drain metal film simultaneously with formation of the thin-film transistor (e.g., Jpn. Pat. Appln. KOKAI Publication No. 2005-93459).
In the outer peripheral portion of the display region of the liquid crystal display panel, the protective line and the common line of the protection circuit, the protective element and the resistance element need to be disposed. As described above, any of them is made of the gate metal film or the drain metal film. Therefore, to insulate them from each other, portions formed of the same conductive film have to be formed apart from each other. In general, in the display region of the transistor array panel, a conductive film pattern for forming a storage capacitance is formed, and this conductive film pattern is electrically connected to common lines of the storage capacitance in the outer peripheral portion of the display region. When the common lines of this storage capacitance are made of the gate metal film or the drain metal film, to insulate these lines from each other, the lines have to be formed apart from each other in one plane. Therefore, the outer peripheral portion of the display region further broadens.